This year's flu shots look like poor match for circulating viruses

◼ Only 48% of the 85 samples of H3N2 influenza viruses that have been tested since Oct. 1 are closely related to the A/Texas/50/2012 strain that was picked for the flu vaccine distributed in North America, according to the agency. Most of the rest of the H3N2 samples were similar to a strain called A/Switzerland/9715293, which was picked for the flu vaccine for the Southern Hemisphere. - LA Times

◼ This season’s flu vaccine may not be as effective against new and possibly more virulent strains of the virus that could become the nation’s dominant form of influenza in the young flu season. - Charlotte Observer

The emergence of a mutated flu virus has caused the Centers for Disease Control and Prevention to issue a national health advisory urging caregivers to prescribe the antiviral medications Tamiflu and Relenza to suspected flu patients, even before they’ve been confirmed to have the virus.

...Antivirals are most effective when taken within 48 hours of the onset of flu symptoms. But fewer than one in six flu patients actually get the drugs, Frieden said.

“It’s very important that we do better. We need to get the message out that treating early with these drugs can make a difference between having a milder illness or a very severe illness,” Frieden said.

Many doctors don’t prescribe antivirals because they mistakenly believe that patients must first be tested for the virus. Others just aren’t familiar with using antivirals for flu treatment because they’re most effective in treating bacterial infections, Frieden said.

The drifted viruses were first detected in March. Frieden said their emergence could have resulted from their attempts to escape the immunity being developed by widespread vaccination. The drifted viruses became prominent in September when it was too late to include them in this year’s vaccine formula. It takes four months to make the vaccine....

Currently, four different strains of flu are circulating in the U.S., and “only time will tell which of them, if any, will predominate for the following weeks and months of this year’s flu season,” Frieden said....